Metered dose inhalers are well known in medicine for treatment, or alleviation of the effects of respiratory complaints, such as asthma. Breath-actuated devices are also known, and have been the subject of many patents.
Many inhalation-actuated dispensing devices are made for use with a pressurized aerosol dispensing container. The dispensing container includes a valve that is normally capable of releasing a metered amount of the aerosol contents, when an internal spring operating the valve is compressed by a sufficient amount. The dispensing device often comprises a chamber having a mouthpiece, air inlets, actuating means for causing the actuation of the valve in the dispensing container, a latching means for releasably retaining said metering valve in a charged position, and an inhalation responsive means for releasing the latch, such that a metered amount of aerosol compound is discharged into the region of the mouthpiece. The overall objective is to give co-ordination of discharge of medicament from the aerosol container with inhalation of the patient, thus allowing a maximum dose of medicament to reach the bronchial passages of the lungs.
U.S. Pat. No. 5,447,150, which is assigned to the assignee of the present disclosure and incorporated by reference herein, discloses a metered dose inhaler. Release of the medicament is actuated through inhalation by a patient through an inhalation-actuated device of the inhaler of the '150 patent.
Prior art inhalers typically include a housing, into which the aerosol medicament canister is removably placed. The canister includes a nozzle at one end which is supported by a structure providing an air flow path leading to a patient-accessible mouthpiece. In many of the prior art inhalers, the aerosol canister is removable from the inhaler housing to permit effective cleaning of the structure defining the airflow path. In some inhalers, the housing is designed to accept a succession of user-introduced aerosol medicament canisters, as well as to provide for canister removal for cleaning.
In the use of these devices, it is desirable that the user know whether the canister in, or about to be placed in, the user's inhaler has an ample supply of doses of medicament for the near term, as well as for the longer term. With that information, a user would know when to replace a given medicament canister.
In the prior art, there have been efforts to obtain and, make available to a user, information indicative of the number of doses dispensed from, or remaining in, a medicament inhaler. By way of example, U.S. Pat. No. 6,446,627, which is also assigned to the assignee of the present disclosure, shows a mechanical counter assembly that is disposed on the housing of an inhaler, where the counter assembly indicates (by way of a visible-to-a-user counter display) a number corresponding to the number of doses dispensed from, or remaining, in a medicament canister. Upon as actuation pursuant to which a dose is dispensed, the counter is driven to increment (in the case where number of doses dispensed doses is indicated, or to decrement in the case where the number of doses remaining is indicated) by way of a mechanical linkage driven by a moving part in the inhaler (for example, motion of the canister relative to the nozzle, in the case of a breath-actuated inhaler of the type described in conjunction with FIGS. 3-6 of U.S. Pat. No. 5,447,150).
While such mechanical count/actuation assemblies do indicate dose count actuation information to a user, subsequently developed prior art inhalers indicate similar information through electronic and/or electromechanical dose counter and indicator assemblies. By way of example, U.S. Pat. Nos. 5,622,163 and 5,544,647 disclose closed capsules, one mounted on a sleeve of an inhaler housing and the other mounted on a base of an aerosol medicament canister. In those patents, the entire dose counter/indicator assembly is a unitary structure, disposed in a closed capsule. Moreover, those disclosed assemblies include a liquid crystal display (LCD) which indicates a multidigit number representative of doses dispensed or remaining in the canister.
Another prior art inhaler with an electronic and/or electromechanical dose counter and indicator assembly is disclosed in U.S. Pat. No. 6,431,168. That patent discloses unitary electronic and/or electromechanical dose counter/actuation indicator assemblies, within a closed or sealed capsule, and having a multidigit LCD for indicating to a user the number of doses dispensed from, or remaining in, an aerosol medicament canister. The electromechanical dose counter indicator assembly is affixed to the canister at the nozzle end of the canister.
In all cases of the above referenced patents, the indication provided to the user by the display, is in the form of a number (of doses dispensed, or doses remaining). In those disclosures, the counter and indicated number is incremented, or decremented, in response to delivery of a dose, or an “actuation” of the inhaler, Thus, to the extent the display indicates “actuation” to the user, such indication must be determined by the user's observation of a transition of the displayed count from one number to the next. Further, there is no information displayed to the user which is directly indicative of the “state of canister”, that is, whether it is “safe” to use (with an adequate number of remaining doses) in a “warning” zone (with a small number of doses left), or in a “danger” zone (with no doses left). The user must draw his/her own conclusions as to the “state of the canister”, by observing the number (not always an easily performed task, particularly by a user with compromised vision or mental abilities) and then determining whether the observed count is in the “safe”, “warning” or “danger” zone.
Moreover, in some of these prior art patents a unitary electronic and/or electromechanical dose counter and actuation indicator assembly is affixed directly to the canister, which in the case of inhaler systems for which it is intended that multiple canisters be sequentially used in a single housing, is relatively costly, because each canister must have its own complete electronic and/or electromechanical dose counter and actuation indicator assembly.
It is an object of the present disclosure to provide a new and improved medicament inhaler having a device which provide an indication to a user of the state of a medicament canister contained in the inhaler.
It is a further object of the present disclosure to provide improved inhalers having canister-associated information stored on a canister for use in generating canister state information for display to a user.
Another object of the present disclosure is to provide improved inhalers with removable medicament reservoirs or canisters, permitting cleaning while providing, on user interrogation, information indicative of the state of the canister.
It is another object to provide inhalers which display to a user, information indicative of the general state of a replaceable medicament reservoir, or canister, contained within the inhaler.
Another object is to provide a medicament reservoir, or canister, bearing a user accessible interrogation assembly to provide information indicative of the state of the canister.